Negative differential resistance devices are implemented to facilitate current flow under different operating conditions. According to an example embodiment of the present invention, an NDR device is arranged for selective passage of current through relatively high tunneling efficiency regions and relatively low tunneling efficiency regions. In some applications, a gate is used to accumulate carriers to facilitate the passage of current that is predominantly one of tunneling current and generation current, respectively, by controlling the passage of current through a relatively high tunneling efficiency region and a relatively low tunneling efficiency region. In some implementations, the NDR device is arranged to mitigate leakage in a storage device using a two-terminal connection.